Retinal dystrophies are diseases that involve degeneration of photoreceptors, the sole light-sensing cells in the retina. A solid understanding of retinal development can contribute to new therapies for combating retinal dystrophies. Recent advances in stem-cell research may make replacement of retinal neurons a feasible therapy for the treatment of many retinal degenerative disorders. In this regard there is currently only a poor understanding of the components of a progenitor cell/stem cell that change as it becomes a particular type of retinal neuron. The purpose of the proposed studies is to apply the powerful techniques of proteomics as a novel research tool in the study of retinal development. Because the ability of a progenitor cell to respond to cues from its environment are reflected in the proteins present in the 'proteome' of the plasma membrane, this project will investigate changes in expression among plasma membrane proteins of retinal progenitor cells from 3 developmental ages. The specific aims of the proposal are (1) To isolate retinal progenitor cells from the developing retina (embryonic days 15 and 18, postnatal day 0), and purify and separate proteins of the plasma membrane. (2) To catalog the proteins of the progenitor cell plasma membrane at these developmental ages, and quantify their levels of expression. Proteins will be identified by using matrix assisted laser desorption ionization-time of flight mass spectrometry, and using generated spectra to search against protein sequence databases. (3) To cluster proteins into theoretical functional groups based on how their level of protein expression changes. This study will be the first to apply the tools of proteomics to retinal development and will pave the way for future developmental studies using this powerful technique. Further, this analysis will identify dozens of proteins and signaling pathways of importance for retinal development, and help to more efficiently focus further studies of differentiation of retinal progenitors.